Microvascular decompression for trigeminal neuralgia: no relation between sensory disturbance and outcome

Trigeminal nerve microvascular decompression (MVD) relieves the pain in a great majority of patients. However, there has been a debate regarding whether the pain-relieving effect is due to the decompression itself or a surgical trauma to the nerve. In 37 consecutive patients, the facial sensibility was quantitatively assessed and the function of other cranial nerves was investigated before and after MVD. The patients were followed for 1-5 years (mean 3.4 years) to assess the surgical outcome. Twelve patients (32%) experienced a mild postoperative sensory deficit assessed by clinical examination. When measured quantitatively with electrical stimulation, sensory thresholds for perception and pain were elevated more than 25% in 16 of the patients (43%). All together 19 patients (51%) did not have any sensory deficit as assessed by either of the two methods used. No severe postoperative cranial nerve dysfunctions were noted in this series. Three patients (8%) had a recurrence of pain at 7-9 months postoperatively. Two of those patients had a moderate elevation of measured sensory thresholds. All 19 patients with no cranial nerve deficits after MVD experienced an excellent pain relief. It seems that trauma to the trigeminal nerve is not a prerequisite for obtaining pain relief after MVD for trigeminal neuralgia.